The present invention relates generally to wrenches, and more particularly to hydraulic wrenches. Specifically the invention relates to a novel hydraulic torque wrench.
Wrenches of many different kinds, including torque wrenches, are well known in the art. Particularly when heavy industrial equipment must be serviced, special tools such as torque wrenches are required to tighten and loosen the large threaded fasteners used in such equipment. These special wrenches must be capable of developing a high, controllable torque.
It is known from the prior art to provide for such applications either impact wrenches, geared wrenches or hydraulic wrenches. All of these are capable of developing high torque, but all of them are subject to various disadvantages that make further developments in this field desirable.
Impact wrenches do develop the same driving torque when operating in two opposite directions. However, they operate constantly at peak power and thus make it impossible in many cases to loosen a fastener, e.g. a corroded nut or bolt, with the same impact that previously tightened it, because corroded fasteners evidently require a higher loosening torque. This cannot be provided in an impact wrench, because such wrenches do not have variable torquing. This may require a mechanic to bring two impact wrenches to the job site, one wrench to loosen the fasteners and another wrench to tighten the fasteners. Moreover, poor control of the striking blows of an impact wrench is frequently observed, resulting in fasteners which are either over-torqued or under-torqued. Evidently, this can lead to damaged fasteners, or to additional time spent in retightening loose fasteners, leading therefore to higher servicing costs.
Gear wrenches are not possessed of the same disadvantages as impact wrenches: however, gear wrenches develop their high torque through large gear reductions, meaning that they operate at a relatively slow rate of speed, which increases the servicing time required for tightening or loosening fasteners with such wrenches. Moreover, because of the large number of gears required in order to obtain the desired speed reduction, gear wrenches are inefficient, and furthermore because of this number of gears the wrenches are necessarily large and cannot be used in many instances where space is limited.
Prior-art hydraulic wrenches, finally are of such construction that they cannot be employed universally. In other words, as a general rule, wrench sockets and reaction members on these wrenches must be exchanged every time a fastener of a different type or size than the previous one is to be tightened or loosened. Evidently, this is time-consuming, quite aside from the fact that different wrench sockets and reaction members must be available at all times for switching over to different jobs. Also, the prior-art hydraulic wrenches require frequent operator adjustment and are subject to frequent jamming, so that they have not found wide acceptance in the industry.